The present invention relates to rolls of the type which are used in paper machines as well as to methods for manufacturing such rolls.
The present invention relates in particular to that type of roll which has an inner roll body which may be solid or in the form of a hollow sleeve and which is covered at its exterior surface by an elongated covering strip which may be helically wound onto the inner roll body with successive turns of the strip engaging the exterior surface of the roll body and pressing against each other. The strip may be formed at the region of its outer edge surface which is directed away from the inner roll body with one or more shoulders which thus provide for the covering strip grooves at the exterior surface of the finished roll, or the side surfaces of the strip can directly engage each other at the outer edge surface of the strip so as to provide the roll with a smooth exterior surface, or any desired combination of smooth and grooved exterior surfaces may be provided for the roll.
Thus, with such a construction the strip has circumferential portions situated one next to the other and surrounding the inner roll body, these circumferential portions forming, for example, successive turns of a helically wound strip. One of the problems encountered with a construction of this type is in connection with the interlocking of the successive turns or circumferential strip portions in such a way that they will not become displaced radially away from the inner roll body. A strip of the latter type is generally made of a corrosion-resistant material, and it is important to prevent moisture from having access to the exterior surface of the inner roll body. Problems are also encountered in known constructions of the above type in connection with preventing moisture from having access to the inner roll body so as to prevent corrosion thereof.
Also, in connection with constructions of the above type it is important to prevent the successive turns of the strip from becoming displaced axially apart from each other. Furthermore, one of the problems encountered in the prior art is in connection with constructing the strip with the degree of precision required in maintaining the successive turns of the strip reliably in engagement with each other at all times.
Thus, the invention relates to a roll of the type which is adapted to be used in a paper machine and which is provided with a roll covering which preferably is of a corrosion-resistant material and which may be either grooved or ungrooved over its exterior surface, or which is made up of grooved and ungrooved portions situated one next to the other along the axis of the roll.
Paper machine roll coverings made of a continuous covering strip by winding such a strip on an inner roll body are already known. For example reference in this connection may be made to U.S. Pat. No. 3,718,959.